Rip the DVD down with DVDDecrypter using file mode. (I think it is the default anyway)
Then open up virtualdubmod.
Then FILE/OPEN VIDEO FILE/ and choose the .VOB file you wish to open (that DVDDecrypter created)
Click OK on any of the other questions it asks about audio etc.
It should load the file after a minute or three.
Go to the start of the bit of Video you want to work on, and press Mark In button(The second last button on the right at the bottom of screen)
Now move forwards a few frames to the end of the bit that you want to work on (you can move forward a frame at a time by pressing the right arrow key on the keyboard)
Press the Mark Out button (the last button) and the bit of selected video should show as blue on the timeline.
Then go to File/Save Image Sequence and choose something lossless like a .tga file or similar.
That's it - you have you sequence of images and can play in photoshop or any other program really.